With the popularity of electronic devices such as mobile phones and tablet PCs, these electronic devices become critical to people's daily work and life. These electronic devices can provide voice messaging services, or information receiving and sending services.
Taking the mobile phone as an example, when a call comes in, the mobile phone will play a music or a ringtone to notify the user to answer the call if it is in a normal mode; and the mobile phone will vibrate to notify the user to answer the call if it is in a vibration mode. However, if the mobile phone is in a silent mode, a screen of the mobile phone may light up, but the mobile phone may not generate any sound or vibration to notify the user to answer the call.
Therefore, when an electronic device is in the silent mode and the screen is in an unobservable state, the electronic device is unable to notify the user to read received messages.